With the fast development of the social economy, currency circulation and requirement for automatic currency processing devices are increasing sharply. Automatic currency processing devices are widely applied in the fields and businesses such as bank, currency sorting center, currency escorting agency, super market, large gas station and retail shopping center.
The anti-counterfeiting feature of a valuable document such as banknote is mainly designed for easy distinguishing and identification by human. For example, the anti-counterfeiting feature of banknotes is designed within a perceptual capability range of human sense including tactile sense, visual sense, auditory sense and the like. And in most anti-counterfeiting designs for the banknotes, the convenience for a machine to acquire the anti-counterfeiting feature of the banknotes has not been considered.
From the view point of signal processing, in the existing methods for discriminating a valuable document based on human perception, only human perceivable contents in the signal, which only constitute minority of the signal, are used, while the rest contents as the majority of the signal are omitted as redundancy. Additionally, as the anti-counterfeiting feature for the banknotes is not designed specially for machine-reading, when a true property of banknotes is identified by a valuable document recognizing system in the automatic currency processing device, only information useable for valuable document recognition is acquired by a sensor in the automatic currency processing device scanning the valuable document. For example, when scanning a number showing a denomination printed in optically variable ink on a 100 denomination banknote of a certain currency type using an optical sensor, image data acquired by the sensor is incapable of reflecting the optical variability serving as the anti-counterfeiting feature. Therefore, processing for the number showing the denomination printed in optically variable ink on the 100 denomination banknote of the currency type only stays on a level of recognizing and can not realize an effect of counterfeit-identifying.
With continuous improvements of technique for forging notes by criminals, the spliced or altered banknotes are quite convincing, even mistakable for the real banknotes, and the forged notes circulating in the society brings enormous challenges to automatic currency processing businesses, affects the social economic order and threatens the national finance security seriously. If the anti-counterfeiting feature of the banknotes can not be used by a machine efficiently and the anti-counterfeiting feature of the banknotes can only be recognized but can not contribute to the accurate counterfeit-identification, the existing financial self-service devices would be put in a passive position by various forged notes and the national finance order and the social harmony and stability would be faced with severe challenges.
Disadvantages in the existing banknote counterfeit-identifying technologies are as follows: the financial self-service device can not read an essential anti-counterfeiting characteristic of the anti-counterfeiting feature on the banknote and does not take full advantage of counterfeit-identifying information of the banknote, thus counterfeit-identifying capability of the financial self-service device is weak.